[Discussion on the history of Pinelliae Rhizoma Praeparatum(Fa banxia) Processing]

Before the Song Dynasty, the main processing method of Pinelliae Rhizoma was soup washing. The "new method" in Taiping Huimin Heji JuFang is a processing method that concocted with Ginger,white alum and starter-making.The "Fa Banxia" in the Yuan Dynasty's Yuyuan Yaofang comes from the Taiping Huimin Heji JuFang, and the Fa Wen Banxia, Fa Bai Banxia, and Fa Hong Banxia are the processing methods of patent medicine with a variety of other herbs.Fa Banxia appeared in the Ming Dynasty, and its auxiliary materials were ginger and white alum, and medical formulary began to include formulas containing Fa Banxia. Bencao Gangmu abbreviates the Yuan Dynasty's Fabai Banxia as "Fa Banxia", and is elaborated under the item attached "prescription" item instead of the "treatment". In the literature of Materia Medica, it is recorded that the preparation of auxiliary materials in Fa Banxia increased, including lime, licorice, soap horn, and simple nitro.After Daoguang in the Qing Dynasty, the Fa Banxia in famous medical cases was more used, and at that time, Fa Banxia was Xian Banxia. There are two recipes for Xian Banxia: one is made with seven processes, and the other is soaked in alum licorice water. During the Republican period, Zhang Cigong also pointed out that Fa Banxia was sliced Xian Banxia after rinsing and boiling, while the preparation method of Xian Banxia was Banxia made of ginger and white alum.Ye Juquan pointed out that the so-called "fa" is neither an ancient method nor a new method, questioning the process of repeated immersion in Banxia. After 1949, the questioning of Fa Banxia continued unceasing.Influenced by this, the 1960 edition Beijing Traditional Chinese Medicine Slice Cutting Experience included the method of soaking alum, licorice ,lime water, and was included in the 1963 edition of the Pharmacopoeia of the People's Republic of China.The 1985 version reduced the soaking time and eliminated the soaking process of alum based on the 1963 version, and this method is still used today.

[Association between clinical phenotypes of hypertrophic cardiomyopathy and Ca2+ gene variation gene variation]

Objective: To observe the association between clinical phenotypes of hypertrophic cardiomyopathy (HCM) patients and a rare calcium channel and regulatory gene variation (Ca²⁺ gene variation) and to compare clinical phenotypes of HCM patients with Ca²⁺ gene variation, a single sarcomere gene variation and without gene variation and to explore the influence of rare Ca²⁺ gene variation on the clinical phenotypes of HCM. Methods: Eight hundred forty-two non-related adult HCM patients diagnosed for the first time in Xijing Hospital from 2013 to 2019 were enrolled in this study. All patients underwent exon analyses of 96 hereditary cardiac disease-related genes. Patients with diabetes mellitus, coronary artery disease, post alcohol septal ablation or septal myectomy, and patients who carried sarcomere gene variation of uncertain significance or carried>1 sarcomere gene variation or carried>1 Ca²⁺ gene variation, with HCM pseudophenotype or carrier of ion channel gene variations other than Ca²⁺ based on the genetic test results were excluded. Patients were divided into gene negative group (no sarcomere or Ca²⁺ gene variants), sarcomere gene variation group (only 1 sarcomere gene variant) and Ca²⁺ gene variant group (only 1 Ca²⁺ gene variant). Baseline data, echocardiography and electrocardiogram data were collected for analysis. Results: A total of 346 patients were enrolled, including 170 patients without gene variation (gene negative group), 154 patients with a single sarcomere gene variation (sarcomere gene variation group) and 22 patients with a single rare Ca²⁺ gene variation (Ca²⁺ gene variation group). Compared with gene negative group, patients in Ca²⁺ gene variation group had higher blood pressure and higher percentage of family history of HCM and sudden cardiac death (P<0.05); echocardiographic results showed that patients in Ca²⁺ gene variation group had thicker ventricular septum ((23.5±5.8) mm vs. (22.3±5.7) mm, P<0.05); electrocardiographic results showed that patients in Ca²⁺ gene variation group had prolonged QT interval ((416.6±23.1) ms vs. (400.6±47.2) ms, P<0.05) and higher RV5+SV1 ((4.51±2.26) mv vs. (3.50±1.65) mv, P<0.05). Compared with sarcomere gene variation group, patients in Ca²⁺ gene variation group had later onset age and higher blood pressure (P<0.05); echocardiographic results showed that there was no significant difference in ventricular septal thickness between two groups; patients in Ca²⁺ gene variation group had lower percentage of left ventricular outflow tract pressure gradient>30 mmHg (1 mmHg=0.133 kPa, 22.8% vs. 48.1%, P<0.05) and the lower early diastolic peak velocity of the mitral valve inflow/early diastolic peak velocity of the mitral valve annulus (E/e') ratio ((13.0±2.5) vs. (15.9±4.2), P<0.05); patients in Ca²⁺ gene variation group had prolonged QT interval ((416.6±23.1) ms vs. (399.0±43.0) ms, P<0.05) and lower percentage of ST segment depression (9.1% vs. 40.3%, P<0.05). Conclusion: Compared with gene negative group, the clinical phenotype of HCM is more severe in patients with rare Ca²⁺ gene variation; compared with patients with sarcomere gene variation, the clinical phenotype of HCM is milder in patients with rare Ca²⁺ gene variation.

[Impact of individual and combined assessment of age- and sex-specific brachial-ankle pulse wave velocity and pulse pressure on all-cause mortality]

Objective: To evaluate the impact of individual and combined assessment of age- and sex-specific brachial-ankle pulse wave velocity (baPWV) and pulse pressure (PP) on all-cause mortality. Methods: This study is a prospective cohort study. Individuals participated in the Kailuan Study and completed baPWV measurements between 2010 and 2016 were included in this study. After stratifying by sex, 75th percentile baPWV and PP values for different age group were calculated at five years interval. BaPWV and PP values below the 75th percentile were defined as normal, and those above or equal to the 75th percentile were defined as increased. The participants were allocated to four groups according to their PP and baPWV status: normal baPWV/PP group, high baPWV/normal PP group, normal baPWV/high PP group and high baPWV/PP group. The primary outcome was all-cause mortality during the follow-up period. Cox proportional hazards models were used to explore the impact of individual and combined assessment of baPWV and PP on all-cause mortality events. Results: A total of 39 339 participants were enrolled in this study, aged (49.3±12.8) years, of which 28 731 (73.03%) were males. There were 23 268, 6 025, 6 210 and 3 836 cases in the normal baPWV/PP group, high baPWV/normal PP group, normal baPWV/high PP group and high baPWV/PP group, respectively. The average follow-up duration was (4.98±2.53) years. During the follow-up period, all-cause mortality occurred in 998 individuals. Multivariate Cox regression analysis showed increased risk of all-cause mortality in the high baPWV/normal PP group (HR=1.27, 95%CI 1.07-1.50), and in the high baPWV/PP group (HR=1.33, 95%CI 1.08-1.65) compared to the normal baPWV/PP group. Increased pulse pressure alone had no impcat on all-cause death (HR=1.06, 95%CI 0.87-1.29). Conclusions: The risk of all-cause mortality significantly increases with increased age-and sex-specific baPWV and PP values. BaPWV may be a better predictor of all-cause mortality than PP in this cohort.

A125 TANDEM STUDY DESIGN IS LESS LIKELY TO DEMONSTRATE IMPROVED ADENOMA DETECTION RATE THAN PARALLEL STUDY DESIGN IN THE ASSESSMENT OF ARTIFICIAL INTELLIGENCE-ASSISTED COLONOSCOPY

Background

Randomized controlled trials have reported that artificial intelligence (AI) improves adenoma detection rate (ADR). Different methodologies, namely parallel and tandem study designs, have been employed to evaluate the efficacy of AI-assisted colonoscopy in randomized controlled trials. In systematic reviews and meta-analyses, a pooled effect that includes both study designs have been reported. However, it is unclear whether there are inconsistencies in the reported results of these two designs.

Purpose

To determine if there are differences in ADR using AI-aided technologies during colonoscopy between parallel and tandem study designs

Method

A systematic search of Ovid MEDLINE (1946 to October 2022) and EMBASE (1947 to October 2022) for randomized controlled trials comparing AI-assisted colonoscopy with routine high-definition colonoscopy in polyp detection was conducted. Reference lists of systematic reviews were searched for additional studies. The publications were divided based on trial design: parallel vs. tandem. Analysis was conducted using Review Manager 5.4.1 using a random effects model.

Result(s)

The search identified 540 articles. After screening the title and abstract for relevance, 19 randomized controlled trials involving a total of 14 657 patients were included for full-text review. Fourteen were parallel studies (14 136 patients) and 5 were tandem studies (521 patients). ADR was reported in 17 studies, and there was overall improvement in ADR with AI-assisted colonoscopy (risk ratio [RR] 1.33, 95% CI 1.22-1.44; p<.0001). Based on a separate pooled analyses of 13 parallel studies and 4 tandem studies, ADR significantly improved with AI assistance compared to routine colonoscopy, regardless of study design (RR 1.35, 95% CI 1.24-1.47 and p<.0001; RR 1.15, 95% CI 1.03-1.28; p=0.02, respectively). A significant increase in ADR with AI assistance were found in 84.6% (11/13) of parallel design studies, but in only 25% (1/4) of tandem studies.

Image

Conclusion(s)

AI assistance during colonoscopy significantly increased ADR in both parallel and tandem studies; however, improvement in ADR was less likely to be seen in tandem compared to parallel studies. It remains unclear why this difference exists, but some hypotheses include smaller sample sizes in the tandem studies, significant heterogeneity in the tandem design, and differences in operator bias depending on study design. Better understanding the differences in these study designs will inform future studies of new endoscopic technologies.

Disclosure of Interest

None Declared

[Myocardial biopsy of Liwen procedure: representability and etiological diagnostic value of cardiac samples obtained by a novel technique in patients with hypertrophic cardiomyopathy]

Objective: To investigate the representability and etiological diagnostic value of myocardium samples obtained from patients with hypertrophic cardiomyopathy (HCM) by transthoracic echocardiography-guided percutaneous intramyocardial septal biopsy (myocardial biopsy of Liwen procedure). Methods: This study was a retrospective case-series analysis. Patients with HCM, who underwent myocardial biopsy of Liwen procedure and radiofrequency ablation in Xijing Hospital, Air Force Military Medical University from July to December 2019, were included. Demographic data (age, sex), echocardiographic data and complications were collected through electronic medical record system. The histological and echocardiographic features, pathological characteristics of the biopsied myocardium of the patients were analyzed. Results: A total of 21 patients (aged (51.2±14.5) years and 13 males (61.9%)) were enrolled. The thickness of ventricular septum was (23.3±4.5)mm and the left ventricular outflow tract gradient was (78.8±42.6)mmHg (1 mmHg=0.133 kPa). Eight patients (38.1%) were complicated with hypertension, 1 patient (4.8%) had diabetes, and 2 patients (9.5%) had atrial fibrillation. Hematoxylin-eosin staining of myocardial samples of HCM patients before radiofrequency ablation evidenced myocytes hypertrophy, myocytes disarray, nuclear hyperchromatism, hypertrophy, atypia, coronary microvessel abnormalities, adipocyte infiltration, inflammatory cell infiltration, cytoplasmic vacuoles, lipofuscin deposition. Interstitial fibrosis and replacement fibrosis were detected in Masson stained biopsy samples. Hematoxylin-eosin staining of myocardial samples of HCM patients after radiofrequency ablation showed significantly reduced myocytes, cracked nuclear in myocytes, coagulative necrosis, border disappearance and nuclear fragmentation. Quantitative analysis of myocardial specimens of HCM patients before radiofrequency ablation showed that there were 9 cases (42.9%) with mild myocardial hypertrophy and 12 cases (57.1%) with severe myocardial hypertrophy. Mild, moderate and severe fibrosis were 5 (23.8%), 9 (42.9%) and 7 (33.3%), respectively. Six cases (28.6%) had myocytes disarray. There were 11 cases (52.4%) of coronary microvessel abnormalities, 4 cases (19.0%) of adipocyte infiltration, 2 cases (9.5%) of inflammatory cell infiltration,6 cases (28.5%) of cytoplasmic vacuole, 16 cases (76.2%) of lipofuscin deposition. The diameter of cardiac myocytes was (25.2±2.8)μm, and the percentage of collagen fiber area was 5.2%(3.0%, 14.6%). One patient had severe replacement fibrosis in the myocardium, with a fibrotic area of 67.0%. The rest of the patients had interstitial fibrosis. The myocardial specimens of 13 patients were examined by transmission electron microscopy. All showed increased myofibrils, and 9 cases had disorder of myofibrils. All patients had irregular shape of myocardial nucleus, partial depression, mild mitochondrial swelling, fracture and reduction of mitochondrial crest, and local aggregation of myofibrillary interfascicles. One patient had hypertrophy of cardiomyocytes, but the arrangement of muscle fibers was roughly normal. There were vacuoles in the cytoplasm, and Periodic acid-Schiff staining was positive. Transmission electron microscopy showed large range of glycogen deposition in the cytoplasm, with occasional double membrane surround, which was highly indicative of glycogen storage disease. No deposition of glycolipid substance in lysozyme was observed under transmission electron microscope in all myocardial specimens, which could basically eliminate Fabry disease. No apple green substance was found under polarized light after Congo red staining, which could basically exclude cardiac amyloidosis. Conclusion: Myocardium biopsied samples obtained by Liwen procedure of HCM patients are representative and helpful for the etiological diagnosis of HCM.

Association between recovered acute kidney injury within 48hours and mortality in patients following coronary angiography: a cohort study

Background

The association of recovered acute kidney injury (AKI) with mortality was controversial. Our study aims to investigate the impact of recovered AKI on mortality in patients following coronary angiography (CAG).

Methods

Our study retrospectively enrolled 3,970 patients with pre-operative serum p creatinine (Scr) and twice measurements within 48hours after procedure. Recovered AKI defined as the diagnosis of AKI (Scr &gt;0.3 mg/dL or &gt;50% from the baseline level) on day 1 when Scr failed to meet the criteria for AKI on the day 2. Maintained AKI was defined as AKI not meeting the definition for recovered AKI. The primary outcome was 1-year all-cause mortality. Multivariable logistic regression was used to assess the association between recovered AKI and 1-year mortality.

Results

Among 3,970 participants, 861 (21.7%) occurred AKI, of whom 128 (14.9%) was recovered AKI and 733 (85.1%) was maintained AKI. 312 (7.9%) patients died within 1-year after admission. After multivariable analysis, recovered AKI was not associated with higher 1-year mortality (adjusted odds ratio [aOR], 1.37; CI, 0.68–2.51) compared without AKI. Among AKI patients, Recovered AKI was associated with a 52% lower 1-year mortality compared with maintained AKI. Additionally, maintained AKI was significantly associated with higher 1-year mortality (aOR, 2.67; CI, 2.05–3.47).

Conclusions

Our data suggested that recovered AKI within 48h was a common subtype of AKI following CAG, without increasing mortality. More attention need to be paid to the patients suffering from maintained AKI following CAG.

Funding Acknowledgement

Type of funding sources: None. Association of AKI and mortalitySubgroups analysis

[Dysregulated proportion of intrahepatic Treg cells and Th17 along with CD8+ T lymphocytes drives disease progression after kasai biliary atresia surgery]

Objective: To analyze the clinicopathological characteristics and intrahepatic immune cells infiltration condition after Kasai biliary atresia surgery. Methods: Data of 28 cases who underwent liver transplantation in the liver transplantation center of our hospital from June 2017 to March 2019 were enrolled. Of which, 20 cases were in the biliary atresia group (divided into two subgroups: 10 cases without Kasai surgery and 10 cases after Kasai surgery, and latter subsided cholestasis) and 8 cases in the control group. Clinical and pathological morphological characteristics of the groups were compared. Liver tissue sections were stained with immunohistochemistry and CD3, CD4, CD8, CD20, Foxp3, and interleukin-17A were quantitatively analyzed. Kruskal-Wallis test was used to measure the above indicators, and rank-sum test or Fisher's exact test was used to compare the count data. Results: The degree of clinical and pathological cholestasis in the biliary atresia group after Kasai surgery was significantly lower than that of the group without Kasai surgery, and the degree of liver fibrosis was also significantly reduced (P < 0.05), but there was no statistically significant difference in the degree of inflammation in the portal vein area between the two groups (P > 0.05). There was statistically significant difference in the types of immune cells infiltrated in the liver (P < 0.05). Compared with the group without Kasai surgery, the infiltration of CD3, CD8, IL-17A and Foxp3 positive cells in the portal vein area after Kasai surgery group (P < 0.05) was significantly reduced, but there was no statistically significant difference in the proportion of Foxp3/CD4 positive cells between the two groups (P > 0.05), which continued to be lower than that of the control group (P < 0.05). Compared with the non-Kasai surgery group, the proportion of Foxp3/IL-17A and Foxp3/CD8 positive cells in the portal vein area did not increase significantly after Kasai surgery group (P > 0.05), and remained lower than the control group. However, the proportion of Foxp3/IL-17A and Foxp3/CD8 positive cells was significantly reduced (P ​​< 0.05). Conclusion: Intrahepatic inflammatory cell infiltration and regulatory/effector T lymphocyte proportion dysregulation exist in patients with subsided cholestasis after Kasai biliary atresia surgery, which may be an important factor to promote the disease progression.

[Implementing and evaluating the online course system of orthodontic education]

A new teaching mode with the combination of online teaching and flipped class was designed and implemented in the Stomatological College of Nanjing Medical University based on the National Online Open Courses, the Virtual Interactive Network Teaching Platform and the E-learning Network Teaching Platform. The new online course system of orthodontic education was constructed with several components including the process and outcome assessments, the professional literature and knowledge summary reports and the virtual interactive online training. With the informative and convenient online teaching resources and modes, students' comprehensive abilities of independent learning were improved.

A95 HOW ENDOSCOPY TEACHERS MAKE POLYPECTOMY ENTRUSTMENT DECISIONS IN CLINICAL AND SIMULATION-BASED SETTINGS

Background

Entrustment, a central construct in competency-based medical education (CBME), represents the point at which clinical supervisors trust a trainee to perform a task independently. Many implementations of CBME involve assessing entrustment through observation of entrustable professional activities (EPAs). While EPAs are frequently assessed in both clinical and simulation-based settings, research has yet to clarify how faculty who teach endoscopy form judgments of entrustment across these two contexts.

Aims

We aimed to explore the features that endoscopy teachers report as influencing their entrustment decisions regarding polypectomy across clinical and simulation-based assessment settings.

Methods

We designed an interview-based, constructivist grounded theory-informed study involving endoscopy teachers and trainees in the University of Toronto gastroenterology residency program. Teachers completed separate EPA assessments of each trainee’s performance of an endoscopic polypectomy (colonic polyps &lt; 1cm, Paris 0-Is or 0-Ip in morphology) in both settings. Teachers were interviewed after each assessment to explore how they made their entrustment decision within and across settings. Transcribed interview data were coded iteratively using constant comparison to generate themes.

Results

Based on 14 interviews with 7 endoscopy teachers, we found that they: (1) held multiple meanings of entrustment for polypectomy, both within and across participants, (2) expressed variability in how they justified their entrustment decisions, the related narrative, and numerical scoring, (3) held unique personal criteria for making decisions ‘comfortably,’ including authenticity of the task, variability in terms of polyp shape, location, and morphology, as well as the ability to assess trainee response to procedural complications (e.g., post-polypectomy bleeding), and (4) perceived a relative freedom when using simulation to make entrustment decisions due to the absence of a real patient.

Conclusions

We found that faculty who teach endoscopy defined polypectomy entrustment in a variety of ways, leading to variability in how they judged entrustment within and across trainees and assessment settings. The observed idiosyncrasies suggest gastroenterology competence committees cannot assume equivalence of EPA data obtained from different settings. Furthermore, educators designing faculty development for CBME will need to attend to the criteria that endoscopy teachers report they need to comfortably make entrustment decisions.

Funding Agencies

Royal College of Physicians and Surgeons of Canada

[Clinicopathological features of Caroli disease/Caroli syndrome: an analysis of 21 cases]

Objective: To summarize and compare clinicopathological features of Caroli disease and Caroli syndrome. Methods: A total of 21 patients diagnosed with Caroli disease or Caroli syndrome in Beijing Friendship Hospital, Capital Medical University, from January 2015 to December 2018 were included. Through the clinical manifestations and comparative analysis of the differences between different clinical types, the liver pathological features of these patients were described. Results: Of all patients included, 8 were male and 13 were female, and the medium age was 13.5 year old. The initial symptom was fever in 6 cases (28.6%), gastrointestinal bleeding in 6 cases (28.6%) and hepatosplenomegaly in 9 cases (42.8%). Caroli disease accounted for 6 cases (28.6%) and Caroli syndrome 15 cases (71.4%). The total bilirubin [6.7 (4.7, 15.0) vs 16.0(10.9, 33.0)μmol/L] and direct bilirubin [1.3(0.9,6.4)vs 3.5(2.7, 16.2)μmol/L] were significantly lower in Caroli disease group in comparison to those in Caroli syndrome group(both P<0.05). The hemoglobin [117.0 (106.0, 126.2) vs 85.0 (74.0, 103.0) g/L] and platelet count [286.0 (149.8, 467.5)×10(9)/L vs 76.1(55.0,123.0)×10(9)/L] in Caroli disease group were significantly higher than those in Caroli syndrome group (both P<0.05). There were 10 patients (47.6%) who underwent liver transplantation. Child-Pugh-Turcotte Score (liver function reserve) were significantly higher than that in the non-liver transplantation group[8.0(8.0, 10.2)vs 5.0 (5.0, 6.0), P<0.05]. Conclusions: Early symptoms of Caroli disease/Caroli syndrome are atypical and prone to misdiagnosis and misdiagnosis. The diagnosis is usually based on pathology and may be supplemented by laboratory examination and imaging analysis.

[The role of three-dimensional speckle tracking imaging derived parameters on predicting outcome of hypertrophic cardiomyopathy patients with MYH7 mutations]

Objective: To evaluate the cardiac functional changes in hypertrophic cardiomyopathy(HCM) patients with β-myosin heavy chain gene (MYH7) mutations by three-dimensional (3D) speckle tracking imaging(3D-STI) and conventional echocardiography modalities, and then to explore the potential predictors of adverse cardiovascular events in these patients. Methods: A consecutive series of 192 HCM patients admitted in our center from October 2014 to October 2016 were genetically screened to identify MYH7 mutations in this retrospective study. A total of 43 HCM patients with MYH7 mutations were enrolled. The patients were divided into events group(n=13) and no event group(n=30) according to the presence or absence of adverse cardiovascular events(primary and secondary endpoints). All patients were followed up to January 2019 after comprehensive evaluation of 3D-STI, two-dimensional and Doppler echocardiography. The adverse cardiovascular events were recorded. Results: The median follow up time was 1 012 (812, 1 330) days. During follow-up, 13 patients (30.2%) reached endpoints: 6 cases of the primary endpoints(2 cases of sudden cardiac death(SCD), 3 cases of survival after defibrillation, and 1 case of appropriate implantable cardioverter-defibrillator(ICD) discharge); 7 cases of the second endpoints(5 cases of heart failure hospitalization, 1 case of syncope and cardioversion due to supraventricular tachycardia, and 1 case of end-stage HCM). Patients with adverse cardiovascular events had higher prevalence of syncope and risk of SCD, enlarged left atrial volume index(LAVI) and reduced 3D left ventricular global longitudinal train (3D-GLS), as compared to those without adverse events(all P<0.05). The multivariate Cox regression analysis showed that reduced 3D-GLS(HR=0.814, 95%CI 0.663-0.999, P=0.049) was an independent predictor for adverse cardiovascular events. The cutoff value of 3D-GLS≤13.67% was linked with significantly increased risk of adverse cardiovascular events in this patient cohort(AUC=0.753, 95%CI 0.558-0.948, sensitivity 86%, specificity 69%, P<0.05). The Kaplan-Meier analysis indicated that the patients with the 3D-GLS≤ 13.67% faced higher risk of death than those with 3D-GLS>13.67%. Conclusion: 3D-GLS is useful on predicting adverse cardiovascular events in HCM patients with MYH7 mutations.

A156 LOW COMPLICATION RATE IN THE OUTPATIENT INTRAJEJUNAL LEVODOPA/CARBIDOPA INTESTINAL GEL CLINICAL PROGRAM

Background

Levodopa/carbidopa intestinal gel (LCIG) is a formulation that is delivered continuously through a percutaneous endoscopy gastro-jejunal tube (PEG-J) for the treatment of patients with advanced Parkinson’s disease (PD). LCIG significantly reduces periods of increased motor symptoms without troublesome dyskinesia. Adverse events related to this treatment have been attributed to PEG-J insertion and the device used for LCIG delivery, rather than to the LCIG preparation itself. To date, the data evaluating long-term efficacy and safety of PEG-J insertion for LCIG administration in the outpatient setting is limited.

Aims

The aim of this study is to describe short and long-term adverse events (AEs) associated with outpatient PEG-J tube insertion for LCIG administration at our centre.

Methods

A retrospective chart review was performed of all PD patients who underwent PEG-J insertion for LCIG therapy at Toronto Western Hospital from March 2011 to October 2019. All AEs associated with PEG-J insertion were collected including procedure and tube related complications, hospital admissions, emergency room (ER) visits and deaths. Data was analyzed using descriptive statistics.

Results

A total of 58 patients were identified and included in the final analysis. 37 (64%) male, with a mean age of 74 years +/-6.17. The mean duration of PD diagnosis prior to PEG-J insertion was 16.5 years +/-2.0. Mean time from PEG-J insertion to data collection was 37.5 months +/- 19.3. 30 (51%) patients had post-procedural abdominal pain or site pain. This pain improved with over the counter analgesics. 9 (16%) had possible site infection; 6 received oral antibiotics and 3 had the tube replaced. 19 (33%) developed granulation tissue, with only 2 patients requiring tube exchange. 32 (55%) had their tube removed or exchanged secondary to PEG-J malfunction. No ER visits related to the PEG-J were recorded. During the data collection period, 12 (21%) patients died for reasons unrelated to PEG-J insertion. There were no reported serious adverse events (SAEs), including post-procedure perforation, bleeding, fistula formation, development of intra-abdominal collections or buried bumper syndrome.

Conclusions

This study demonstrates the absence of serious AEs associated with outpatient PEG-J insertion for LCIG administration in patients with advanced PD. The most common short-term AE was post-procedural pain. The most common long-term AE was related to PEG-J malfunction requiring replacement. This study supports that the current method of outpatient PEG-J insertion for the administration of LCIG is safe in patients with advanced PD.

Funding Agencies

None

A179 CANADIAN INVOLVEMENT IN THE EVALUATION OF NOVEL THERAPY FOR DIABETIC GASTROPARESIS: OVERVIEW OF PLEDGE TRIALS

Background

Diabetic gastroparesis(DG) is a serious, chronic complication of type 1 or 2 diabetes mellitus(DM) presenting with a delay in gastric emptying(GE). An estimated 3 million Canadians have been diagnosed with DM; up to 5% of these patients may develop DG. DG can result in poor glycemic control, recurrent nausea and vomiting, often resulting in hospitalization. To date, no effective treatments are available. A phase 2 study showed that relamorelin (RLM), a synthetic ghrelin agonist, was safe and effective in treating DG. Investigators across Canada are participating in a set of phase 3 international trials of RLM in the treatment of DG.

Aims

To report the Canadian involvement in the international effort to evaluate the safety and efficacy of RLM in the treatment of DG. PLEDGE is a set of 5 trials: two identical 12-week studies, a 46-week extension study, a 52-week exposure study, and an open-label extension study. Collectively, the data from these studies will help to evaluate the safety and efficacy of RLM, a novel treatment for Canadian patients living with DG.

Methods

Four global, multicenter, randomized, double-blind, placebo-controlled, parallel-group studies compare the efficacy of RLM with placebo in participants with DG using composite endpoints of nausea, abdominal pain, postprandial fullness, bloating. Participants are randomized to RLM 10μg or placebo subcutaneously (SC) twice daily groups. The open-label continuation of treatment will follow participants until RLM becomes commercially available to provide long-term safety information to support the safe use of RLM as a chronic treatment of DG. As seen in Figure 1, participants from the two 12-week studies will rollover into the third study that will continue for 46 weeks. The fourth study will enroll participants that were not randomized in the first two studies because their symptoms were less severe and will also accept new participants. Participants will be randomized 2:1 to RLM 10μg or placebo SC twice daily groups. Participants from the third and fourth studies have the option to enroll in the open-label study.

Results

Target enrollment is approx. 1800 participants for the 4 global, multicenter, randomized, double-blind, placebo-controlled, parallel-group studies and 1000 participants for the open label study. 700 sites are expected to participate globally; 15 Canadian sites in 6 provinces are participating.

Conclusions

Canadian centers are actively involved in the PLEDGE trials to help determine the efficacy and safety of RLM, a potential new treatment for DG. This publication increases awareness of the Canadian gastroenterology community, providing an option to refer interested patients to PLEDGE study centers.

Funding Agencies

None

A133 DEVELOPMENT OF TYPE 3 ACHALASIA WITH DISTANT PANCREATIC MALIGNANCY

Background

Pseudoachalasia is often caused by malignant involvement at the gastroesophageal junction (GEJ) leading to dysphagia.

Aims

We describe a case of type 3 achalasia presenting in a woman with metastatic pancreatic cancer with no direct involvement at the GEJ, fundus or cardia.

Methods

A case report and literature review were performed.

Results

A 53-year-old woman presented with a 2-month-history of progressive abdominal pain, nausea and vomiting with a 30-pound weight loss. She had a remote history of breast cancer in remission after surgery and chemoradiation. On presentation, she denied chest pain, reflux, dysphagia or odynophagia. Abdominal exam revealed focal epigastric tenderness and jaundice. Abdominal CT showed a 6.7 x 5.8 cm conglomerate mass involving the hepatic hilum, pancreatic head, duodenum, common bile duct, and portal vein with gastric outlet and biliary obstruction. This mass was confirmed to be a pancreatic adenocarcinoma on pathology. She then underwent nasogastric tube decompression. Initial esophagogastroduodenoscopy (EGD) confirmed a stenotic area at the distal duodenal cap. A duodenal stent and common bile duct stent were placed during a second EGD. The esophagus and GEJ were unremarkable on both endoscopic exams. She was started on chemotherapy with gemcitabine and abraxane. Two weeks after her stent placement, she rapidly developed severe retrosternal squeezing discomfort and choking occurring with swallowing. CT chest and abdomen were negative for any intrathoracic and diaphragmatic involvement with stability of the mass. A barium swallow study demonstrated tertiary contractions in the thoracic esophagus with marshmallow hold-up in the distal esophagus. She then underwent a high-resolution esophageal manometry study that demonstrated an elevation of integrated residual pressure (IRP) of the lower esophageal sphincter (LES) and absence of peristalsis, with the distal 2/3rds of the esophagus showing a simultaneous and prolonged pressure front consistent with type 3 achalasia, Chicago classification v3.0 [Figure 1]. All contractions had a distal contractile integral (DCI) of &gt;8000 mmHg-cm-s. She experienced significant symptom improvement with pinaverium bromide, a gut-specific calcium channel antagonist.

A review of the literature revealed that there have been 4 English-language cases published on pseudoachalasia associated with pancreatic cancer, with all cases describing direct infiltration of pancreatic cancer in the GEJ, cardia or fundus with manometric features of type I achalasia.

Conclusions

We report the first case of type 3 achalasia with no evidence of direct malignant infiltration at the GEJ on radiographic and endoscopic evaluations. Possible mechanisms to explain this phenomenon include paraneoplastic antibody-mediated impairment of enteric neurons that decrease nitric oxide availability, or microscopic disease involvement at the GEJ.

Funding Agencies

None

A123 GASTROINTESTINAL SYMPTOMS AND DISORDERS OF GUT BRAIN INTERACTION ARE COMMON IN PATIENTS WITH EHLERS-DANLOS SYNDROME (EDS) IN TERTIARY REFERRAL CENTER

Background

Ehlers Danlos Syndrome (EDS) is a group of rare connective tissue disorders. Gastrointestinal (GI) symptoms such as abdominal pain, nausea, vomiting, bloating and altered bowel habits are common in patients with EDS. Specifically, disorders of gut brain interaction (DGBI) appear to be more common in this patient population. The University Health Network (UHN) has the first and only multi-disciplinary clinic, including specialized gastroenterology services, in Canada for the management of EDS.

Aims

The aim of this study is to describe the GI symptoms and DGBI that are present in our cohort of EDS patients.

Methods

A retrospective chart review of all EDS who were seen in the gastroenterologist clinic of the GoodHope EDS clinic at UHN were reviewed from November 1, 2017 to September 26, 2019. Demographic information including age, sex and EDS subtype were collected. GI symptoms that were collected include constipation, diarrhea, fecal incontinence, nausea, vomiting, bloating, abdominal pain, early satiety, heart burn, dysphagia and regurgitation. A physician made diagnosis of irritable bowel syndrome (IBS) was recorded. Descriptive statistics were performed.

Results

The charts of 79 EDS patients were reviewed; 4 were excluded due to missing data. 75 patients were included in the final analysis. 93.3% of patients were female with a mean age of 36.4 +/- 12.5 years. Of these 75 patients, 43 (57.3%) had EDS-hypermobile subtype, 13 (17.3%) EDS-classic, 3 (4%) EDS-vascular, 3 (4%) unknown EDS subtype and 13 (17.3%) were categorized as having a hypermobile spectrum disorder. The most common GI symptoms observed in this patient group included abdominal pain in 85.5%, bloating in 64.4%, heartburn in 61.8%, constipation in 57.9%, nausea in 50%, diarrhea 43.4%, dysphagia in 43.4%, regurgitation in 34.2%, early satiety in 32.89%, vomiting in 30.2%,and fecal incontinence in 13.1%. It was also observed that 50.7% (n=38) had a physician made diagnosis of IBS. Of these patients with IBS, 16 (42.1%) had IBS constipation, 12 (31.5%) had IBS mixed, and 10 (26.3%) had IBS diarrhea.

Conclusions

Our study demonstrated that GI symptoms are common in patients with EDS. In our cohort, abdominal pain is the most commonly reported GI symptom, though other various GI symptoms are also reported in high numbers. DGBI are also common, with IBS being much more common than what has been reported in the general population. Further studies are needed to better understand the pathophysiology and impact of these GI symptoms and DGBI in patients with EDS.

Funding Agencies

UNH Foundation Goodhope Fund

A125 ABNORMAL REFLUX IS UNCOMMON IN PATIENTS PRESENTING WITH ISOLATED OROPHARYNGEAL SYMPTOMS

Background

Gastroesophageal reflux disease (GERD) is often implicated as a potential etiology for various oropharyngeal (OP) symptoms. Although ambulatory reflux monitoring has been recommended by professional societies for the assessment of OP symptoms, it is unclear if objective measures of acid exposure in the esophagus correlate with the presence of these OP symptoms.

Aims

The aim of this study is to determine the prevalence of abnormal 24-hour pH monitoring in patients presenting with various OP symptoms in our motility unit.

Methods

A retrospective chart review was performed on all patients referred for 24-hour pH monitoring for the evaluation of OP symptoms to the open-access Clinical Motility Unit at the University Health Network between January 1, 2008 and June 1, 2019. Seven symptom categories were examined including cough, globus, throat discomfort, voice change, dental erosion, altered taste, and sensation of phlegm in the throat. The results of the 24-hour pH monitoring were collected. A test was considered abnormal if while off anti-secretory therapy the overall acid exposure (pH &lt; 4) in the distal esophagus was greater than 4.2% of the total time or if while on anti-secretory therapy the overall acid exposure in the esophagus was greater than 1.2% of the time. Descriptive statistics were performed to analyze the data.

Results

384 patients were included in the final analysis. 167 patients (43.5%) presented with cough, 63 (16.4%) with globus, 86 (22.4%) with throat discomfort, 19 (5.9%) with voice changes, 13 (3.4%) with dental erosion, 17 (4.4%) with altered taste and 19 (4.9%) with sensation of phlegm in the throat. Overall, 19.5% of patients presenting with oropharyngeal symptoms had abnormal 24-hour pH monitoring. Abnormal 24-hr pH monitoring was present in 24.6% of those with cough, 15.9% of those with globus, 16.3% of those with throat discomfort, 21.1% of those with voice changes, 23.1% of those with dental erosion, 5.9% of those with altered taste and 10.5% of those with sensation of phlegm in the throat.

Conclusions

This study demonstrates that only a small proportion of patients with OP symptoms have abnormal gastroesophageal acid reflux based on objective 24-hour pH monitoring. Given these findings, future studies to examine the factors that predict having abnormal 24-hour pH monitoring in patients presenting with OP symptoms will help guide resource management of motility testing to determine which patients would benefit most from this type of evaluation.

Funding Agencies

None

A144 A MULTIDISCIPLINARY TEAM APPROACH REDUCES PEG SITE COMPLICATIONS

Background

Education provided to patients and their family on how to care for the percutaneous enteroscopic gastrotomy (PEG) tube is limited and varies widely. This can result in site and tube complications, patient discomfort and increased health care utilization. In addition, a lack of practitioner expertise and variability in practice can affect timely treatment of PEG site complications. Continuous Levodopa/Carbidopa Intestinal Gel (LCIG) has become a standard of treatment option for patients with advanced Parkinson Disease. This medication is delivered by a jejunal tube through a PEG tube (PEG-J). Previous studies in this population reported up to 40% of adverse events related to the PEG site. At Toronto Western Hospital, we developed a multidisciplinary team (MDT), involving a gastroenterologist, a clinical nurse specialist (CNS) with expertise in wound and stoma care and the movement disorder clinical nurse to care for the PEG-J in this patient population.

Aims

To evaluate the effectiveness of our MDT in reducing PEG site complications and health care utilization.

Methods

Consecutive PEG-J patients (n=33) assessed by the MDT between October 2018 and September 2019 were provided standard education on the routine care and maintenance of PEG site complications. The CNS uses a systematic approach to prevent, assess and treat PEG site complications. Before and after the MDT approach, patients were seen the day after the PEG insertion (POD 1), 2 weeks after (titration) and then ad hoc determined by incidence of mild, moderate and severe complications. Post implementation of a MDT approach, patients are seen POD 1, at titration and every 3–6 months during routine visits to the Movement Disorder Clinic. Table 1 outlines classification and suggested treatment based on severity for mild, moderate and severe PEG site complications.

Results

The systematic MDT approach completely eliminated all unscheduled, urgent contact to the health care providers by patients who have been assessed and provided education by the MDT (n=33), including new PEG-J (n=7) and previously inserted PEG-J (n=26). 28.5% of new PEG-J patients had moderate or severe site complication rate, 71.5% had mild or no complications. In the group of patients with previously inserted PEG-J tubes, 58% had moderate or severe site complications, 42% had mild or no complications.

Conclusions

An interprofessional MDT systematic approach drastically reduces PEG site complications and urgent health care utilization. Patients who receive standardized education pre- and post-insertion have a lower incidence of moderate or severe classification of PEG site complications and unscheduled clinic visits.

Funding Agencies

None

[EASL clinical practice guidelines recommendations for drug-induced liver injury in 2019]

Idiosyncratic (unpredictable) drug-induced liver injury (iDILI) is one of the most challenging liver diseases encountered by hepatologists due to its diverse clinical and pathological manifestations and lack of specific diagnostic markers. An increasing awareness of iDILI diagnosis and carefully excluding liver damage induced by other causes is the key to a proper diagnosis of iDILI. However, delayed diagnosis, inappropriate monitor and care leads to serious clinical consequences, such as acute liver failure or even liver-related death. In addition, there is presently no effective treatment for iDILI. Herein, we presented the main recommendations of the recent EASL published first DILI guidelines into Chinese language to facilitate liver disease authors and health workers to understand the latest research progress of DILI.

[Efficacy and safety of transthoracic echocardiography-guided percutaneous intramyocardial septal radiofrequency ablation for the treatment of patients with obstructive hypertrophic cardiomyopathy]

Objective: To investigate the safety and efficacy of transthoracic echocardiography-guided percutaneous intramyocardial septal radiofrequency ablation (PIMSRA) in patients with hypertrophic obstructive cardiomyopathy (HOCM). Methods: Nine HOCM patients with interventricular septal thickness ≥15 mm and ≤25 mm who were treated with PIMSRA between October 2016 to March 2017 in the Hypertrophic Cardiomyopathy Center of Xijing Hospital of Air Force Military Medical University were enrolled,and the clinical data were retrospectively analyzed.Interventricular septum thickness, left ventricular outflow tract diameter and maximum gradient were measured by transthoracic echocardiography immediately after procedure, at 1 month, 3 months and 6 months after operation.Symptoms and New York Heart Association (NYHA) functional class were assessed, and provoked left ventricular outflow tract gradient and exercise time were measured after 6 months. Results: The anterior interventricular septum ((21.5±2.6) mm vs. (24.7±2.7) mm, P<0.05) and posterior interventricular septum (21.1±2.5) mm vs. (22.6±3.3) mm, P<0.05) were significantly increased,left ventricular outflow tract diameter was widened ((8.2±3.4) mm vs. (4.8±2.2) mm, P<0.05), left ventricular outflow tract gradient ((26.8±19.6) mmHg (1 mmHg=0.133 kPa) vs. (83.3±32.4) mmHg, P<0.05) and mitral regurgitation (2.0±1.9) ml vs. (3.2±3.0) ml, P<0.05) were significantly decreased immediately after ablation compared with pre-operation values. Anterior interventricular septum, posterior interventricular septum and left ventricular outflow tract gradient further decreased after 1 month ((17.5±2.0) mm vs. (24.7±2.7) mm, P<0.05; (16.9±2.1) mm vs. (22.6±3.3) mm, P<0.05; (11.6±4.0) mmHg vs. (26.8±19.6) mmHg, P<0.05, respectively) compared with values immediately after ablation. Anterior interventricular septum and posterior interventricular septum decreased after 3 and 6 months ((14.8±1.7) mm and (13.4±2.0) mm vs. (17.5±2.0) mm, all P<0.05; (12.9±1.9) mm and (12.3±2.4) mm vs. (16.9±2.1) mm, all P<0.05, respectively) compared with values at 1 month after ablation.There were no significantly difference in left ventricular outflow tract gradient at 3 and 6 months post procedure compared with 1 month after ablation (all P>0.05). Compared with pre-operation, provoked left ventricular outflow tract gradient decreased ((25.5±11.4) mmHg vs. (147.8±58.0) mmHg, P<0.01), and total exercise time increased ((9.3±1.6) minutes vs. (6.7±1.6) minutes, P=0.03) at 6 months after operation.The symptoms were disappeared in 5 patients. There were 2 cases with NYHA class Ⅱ and 7 cases with NYHA class Ⅲ before operation,while there were 6 patients with NYHA classⅠ and 3 patients with NYHA class Ⅱ at 6 months after operation (P<0.01). Conclusion: Transthoracic echocardiography-guided PIMSRA is a safe and effective new treatment approach for patients with obstructive hypertrophic cardiomyopathy.

[Operative method choice and strategy of laparoscopic surgery therapy for gallbladder stones and common bile duct stones]

Objective: To explore the selection method and technology of laparoscopic surgery for gallbladder stones and common bile duct stones(GCBDS). Methods: Data was collected from 318 in-patients of GCBDS at Department of General Surgery,Xuanwu Hospital of Capital Medical University from January 2013 to December 2017, and 298 in-patients acceptedlaparoscopic cholecystectomy(LC) and choledocholithotomy were recruited into final analysis.There were 138 males and 160 females,aged (60.4±18.6)years (range:25-89 years).Retrospective analysis was done on method distribution,effect and safety of laproscopic surgery.Comparisons of basic characters and therapeutic effects were performed betweenlaparoscopic common bile duct exploration (LCBDE) combined with primary closure and T tube drainage(TTD). Results: Among therecruited in-patients,LC combined with common bile duct exploration was performed in 7 cases(2.3%, 7/298), LC combined with LCBDE was performed in 291 cases(97.7%,291/298).There were 133 cases (45.7%,133/291) who treated by LCBDE combined with TTD and 158 cases(54.3%,158/291) who treated by LCBDE combined with primary closure.In LCBDE combined with primary closure group,18 cases (11.4%,18/158)had intraoperative biliary manometry.All patients were followed up for 6 months at least and there no death.Postoperative complications rate was 10.0% (29/291).There were no significant differences in sex ratio,age,American Society of Anesthesiologists score,concomitant diseases and previous abdominal surgery history between LCBDE combined with primary closure and LCBDE combined with TTD group.Patients in LCBDE combined with primary closure group were accompanied with less acute cholangitis than TTD group (43.3% vs.76.7%; χ(2)=9.061, P=0.002).There were no significant differences in the diameter of common bile duct, the number of stones, hospitalization expenses and the incidence of complications between the two groups(all P>0.05).LCBDE combined with primary closure had shorter operation time ((134.2±28.3)minutes vs.(148.3±19.6)minutes; t=-1.830, P=0.011)and post-operative hospitalization time ((5.6±2.6)days vs. (7.2±2.4)days; t=-1.847,P=0.014).Bile duct leakage rate was higher in primary closure group(6.3% vs.0.8%, χ(2)=3.934, P=0.047) and TTD group had higher residual stones rate(6.8% vs.1.3%; χ(2)=6.008, P=0.014). Conclusion: Strategy for treating GCBDS by laparoscopic surgery should be considered preoperative evaluation and intraoperative exploration to select appropriate minimally invasive surgical methods and techniques.

[Predicting value of 2014 European guidelines risk prediction model for sudden cardiac death (HCM Risk-SCD) in Chinese patients with hypertrophic cardiomyopathy]

Objective: To evaluate the predicting value of the 2014 European Society of Cardiology (ESC) guidelines risk prediction model for sudden cardiac death (HCM Risk-SCD) in Chinese patients with hypertrophic cardiomyopathy (HCM), and to explore the predictors of adverse cardiovascular events in Chinese HCM patients. Methods: The study population consisted of a consecutive 207 HCM patients admitted in our center from October 2014 to October 2016. All patients were followed up to March 2017. The 5-year SCD probability of each patient was estimated using HCM Risk-SCD model based on electrocardiogram, echocardiography and cardiac magnetic resonance (CMR) examination results. The primary, second, and composite endpoints were recorded. The primary endpoint included SCD and appropriate ICD therapy, identical to the HCM Risk-SCD endpoint. The second endpoint included acute myocardial infarction, hospitalization for heart failure, thrombus embolism and end-stage HCM. The composite endpoint was either the primary or the second endpoint. Patients were divided into the 3 categories according to 5-year SCD probability assessed by HCM Risk-SCD model: low risk group<4%,intermediate risk group ≥4% to<6%, and high risk group≥6%. Results: (1) Prevalence of endpoints: All 207 HCM patients completed the follow-up (350 (230, 547) days). During follow-up, 8 (3.86%) patients reached the primary endpoints (3 cases of SCD, 3 cases of survival after defibrillation, and 2 cases of appropriate ICD discharge); 21 (10.14%) patients reached the second endpoints (1 case of acute myocardial infarction, 16 cases of heart failure hospitalization, 2 cases of thromboembolism, and 2 cases of end-stage HCM). (2) Predicting value of HCM Risk-SCD model: Patients with primary endpoints had higher prevalence of syncope and intermediate-high risk of 5-year SCD, as compared to those without primary endpoints (both P<0.05). (3) Predicting value of HCM Risk-SCD model: The low risk group included 122 patients (59%), the intermediate risk group 42 (20%), and the high risk group 43 (21%). There was a clear trend towards to higher heart rate, higher values of PTF(V1) and plane QRS-T angle, higher left ventricular mass index (LVMI), elevated maximal left ventricular outflow tract pressure gradient (LVOT-PGmax), enlarged left atrial dimension(LAD) and volume index (LAVI), reduced systolic mitral annular velocity (s'), and higher late gadolinium enhancement (LGE) volume and mass in patients with high risk of 5-year of SCD, as compared to those with low-intermediate risk (all P<0.05). Moreover, 5-year SCD probability was positively correlated with heart rate, plane QRS-T angle, LVMI, LAVI, LGE%, and negatively correlated with s'(r=0.161, P=0.019; r=0.669, P=0.001; r=0.206, P=0.004; r=0.284, P=0.000; r=0.351, P=0.000; r= -0.245, P=0.001; respectively). (4) LAD, LAVI, e' and s' were independent predictors for poor outcomes. HCM patients with LAD≥39 mm, LAVI≥49.6 ml/m(2), e'≤6.5 cm/s and s'≤6.6 cm/s were more likely to have adverse cardiovascular events (AUC 0.702, 95%CI 0.604-0.799, P=0.001; AUC 0.700, 95%CI 0.567-0.833, P=0.001; AUC 0.716, 95%CI 0.616-0.817, P=0.000; AUC 0.764, 95%CI 0.676-0.853, P=0.000,respectively). Conclusions: The HCM Risk-SCD model is of value in predicting SCD for Chinese HCM patients. The plane QRS-T angle and LGE% are the best predictors of 5-year SCD risk in Chinese HCM patients. Moreover, conventional echocardiographic parameters, including LAD, LAVI, e' and s', are useful to predict adverse cardiovascular events among Chinese HCM patients.

Characterization of RsMYB28 and RsMYB29 transcription factor genes in radish (Raphanus sativus L.)

Glucosinolates (GSLs) are important secondary metabolites in Brassicaceae plants. Previous studies have mainly focused on GSL contents, types, and biosynthesis-related genes, but the molecular characterization patterns of GSL biosynthesis-related transcription factors remain largely unexplored in radish (Raphanus sativus L.). To isolate transcription factor genes regulating the GSL biosynthesis, genomic DNA and cDNA sequences of RsMYB28 and RsMYB29 genes were isolated in radish. Two R2R3-MYB domains were identified in the deduced amino acid sequences. Subcellular localization and yeast-one hybrid assays indicated that both the RsMYB28 and RsMYB29 genes were located in the nucleus and possessed transactivation activity. Reverse transcription quantitative analysis showed that the RsMYB28 and RsMYB29 genes were expressed in seeds, leaves, stems, and roots at the seedling, taproot thickening, and mature stages. Both genes were highly expressed during the seedling and taproot thickening stages. The expression level of RsMYB28 was found to be up-regulated following wounding, glucose, and abscisic acid treatments, whereas RsMYB29 was up-regulated following wounding and methyl jasmonate treatments. These results provide insights into the biological function and characterization of the RsMYB28 and RsMYB29 genes, and facilitate further dissection of the molecular regulatory mechanism underlying the GSL biosynthesis in radish.

Muscarinic activation of transient inward current and contraction in canine colon circular smooth muscle cells

Muscarinic receptor mediated membrane currents and contractions were studied in isolated canine colon circular smooth muscle cells. Carbachol (10(-5) M) evoked a slow transient inward current that was superimposed by a transient outward current at holding potentials greater than -50 mV. Carbachol contracted the cells by 70 +/- 2%. The effects of carbachol were blocked by atropine (10(-6) M), tetraethyl ammonium (20 mM), and BAPTA-AM (25 mM applied for 20 min). The inward current and contraction were not sensitive to diltiazem (10(-5) M), nitrendipine (3 x 10(-7) M), niflumic acid (10(-5) M), or N-phenylanthranilic acid (10(-4) M), but were gradually inhibited after repetitive stimulations in Ca2+ free solution. Ni2+ (2 mM) inhibited the inward current by 67 +/- 4%. The inward current reversed at +15 mV. The outward component could be selectively inhibited by iberiotoxin (20 nM) or by intracellular Cs+. Repeated stimulation in the presence of cyclopiazonic acid (CPA, 3 microM) inhibited the carbachol-induced outward current and partially inhibited contraction. CPA did not inhibit the inward current. In conclusion, muscarinic receptor stimulation evoked a CPA-sensitive calcium release that caused contraction and a CPA-insensitive transient inward current was activated that is primarily carried by Ca2+ ions and is sensitive to Ni2+.

Mus and Peromyscus chromosome homology established by FISH with three mouse paint probes

Fluorescence-labeled DNA probes constructed from three whole house mouse (Mus domesticus) chromosomes were hybridized to metaphase spreads from deer mouse (Peromyscus maniculatus) to identify homologies between the species. Mus Chr 7 probe hybridized strongly to the ad-centromeric two-thirds of Peromyscus Chr 1q. Most of Mus 3 probe hybridized principally to two disjunct segments of Peromyscus Chr 3. Mus Chr 9 probe hybridized entirely to the whole Peromyscus Chr 7. Three Peromyscus linkage groups were assigned to chromosomes, based on linkage homology with Mus. The data also are useful in interpretation of chromosomal evolutionary history in myomorphic rodents.

Development of pacemaker activity and interstitial cells of Cajal in the neonatal mouse small intestine

Intestinal motor patterns are not well developed in premature infants. Similarly, in neonatal mice, irregular motor patterns were observed. Pacemaker cells, identified in the small intestine as interstitial cells of Cajal (ICCs) associated with Auerbach's plexus (ICC-APs), contribute to the generation of peristaltic movements. The objective of the present study was to assess the hypothesis that abnormal gut motor activity in (preterm) newborns can be associated with underdeveloped ICCs. Specifically, the aim was to identify at which point the electrical pacemaker activity is fully developed and whether or not the development of pacemaker activity has a structural correlation with the developmental stage of ICCs. Pacemaker activity was identified as that component of the slow wave that is insensitive to L-type calcium (Ca2+) channel blockers and displays a characteristic reduction in frequency in the presence of cyclopiazonic acid (CPA), a specific inhibitor of the endoplasmic reticulum Ca2+ pump. In newborn, unfed neonates, action potentials occurred that were irregular in frequency and amplitude and sensitive to verapamil. CPA (5 microM) abolished all action potentials. Quiescent spots were observed in approximately 50% of impalements. Six hours after birth, slow-wave activity appeared at a regular frequency and amplitude, and a well-defined plateau phase was observed. Verapamil did not affect the frequency, 5 microM CPA decreased it. The effect of CPA on the pacemaker frequency 2 days after birth was identical to that observed in adult mice. In 2-hr-old neonates, ICCs could be identified through selective uptake of methylene blue, but ultrastructural features were not fully developed. At 48 hr, a complete ICC network covering Auerbach's plexus was formed, confirmed by electron microscopy. In summary, the pacemaker component of the slow waves can be identified in neonates as early as 6 hr after birth. The pacemaker component was fully developed 2 days after birth. These electrophysiological observations correlated with the development of full network characteristics of ICC-APs and the development of fully differentiated ICC-APs from "blast-like" cells.

Development of pacemaker activity and interstitial cells of Cajal in the neonatal mouse small intestine

Intestinal motor patterns are not well developed in premature infants. Similarly, in neonatal mice, irregular motor patterns were observed. Pacemaker cells, identified in the small intestine as interstitial cells of Cajal (ICCs) associated with Auerbach's plexus (ICC-APs), contribute to the generation of peristaltic movements. The objective of the present study was to assess the hypothesis that abnormal gut motor activity in (preterm) newborns can be associated with underdeveloped ICCs. Specifically, the aim was to identify at which point the electrical pacemaker activity is fully developed and whether or not the development of pacemaker activity has a structural correlation with the developmental stage of ICCs. Pacemaker activity was identified as that component of the slow wave that is insensitive to L-type calcium (Ca2+) channel blockers and displays a characteristic reduction in frequency in the presence of cyclopiazonic acid (CPA), a specific inhibitor of the endoplasmic reticulum Ca2+ pump. In newborn, unfed neonates, action potentials occurred that were irregular in frequency and amplitude and sensitive to verapamil. CPA (5 microM) abolished all action potentials. Quiescent spots were observed in approximately 50% of impalements. Six hours after birth, slow-wave activity appeared at a regular frequency and amplitude, and a well-defined plateau phase was observed. Verapamil did not affect the frequency, 5 microM CPA decreased it. The effect of CPA on the pacemaker frequency 2 days after birth was identical to that observed in adult mice. In 2-hr-old neonates, ICCs could be identified through selective uptake of methylene blue, but ultrastructural features were not fully developed. At 48 hr, a complete ICC network covering Auerbach's plexus was formed, confirmed by electron microscopy. In summary, the pacemaker component of the slow waves can be identified in neonates as early as 6 hr after birth. The pacemaker component was fully developed 2 days after birth. These electrophysiological observations correlated with the development of full network characteristics of ICC-APs and the development of fully differentiated ICC-APs from "blast-like" cells.

Interstitial cells of Cajal: mediators of communication between circular and longitudinal muscle layers of canine colon

The network of interstitial cells of Cajal associated with Auerbach's (myenteric) plexus in the canine colon was investigated to determine its role in facilitating communication between circular and longitudinal muscle layers. Electrical coupling between the muscle layers was demonstrated by propagating extracellularly evoked electrotonic pulses from circular muscle cells to nearby longitudinal muscle cells. The likelihood of cytoplasmic continuity across Auerbach's plexus was further demonstrated by the ability of neurobiotin to spread between the interstitial cells and the circular and longitudinal muscle cells. Importantly, direct neurobiotin spread between circular and longitudinal muscle cells was not observed even when they were in close proximity as determined by confocal microscopy. When neurobiotin did spread across the two muscle layers, the intervening interstitial cells were always neurobiotin-positive. In regions where circular and longitudinal muscle cells approach each other closely, electron microscopy revealed the presence of close appositions between interstitial cells and smooth muscle cells. Gap junctions between interstitial cells and smooth muscle cells of both layers, as judged by electron microscopy, were extremely rare. Neither gap junctions nor close appositions were observed between longitudinal and circular muscle cells. The special arrangement for electrotonic coupling across Auerbach's plexus through interstitial cells of Cajal suggests controlled coupling between the two muscle layers, explaining the preservation of their distinct electrical activities.

Circular muscle lamellae of canine colon are electrically isolated functional units

The circular muscle (CM) layer of canine colon consists of circumferentially oriented lamellae separated by connective tissue septa. These lamellae facilitate circumferential ring contractions. Communication between CM lamellae is necessary to generate coordinated, propulsive phasic contractions to create peristaltic movement. Potential roles of the submuscular network of interstitial cells of Cajal and branching smooth muscle cells (ICC-bSM), the myenteric interstitial cells of Cajal network (ICC-AP), and the longitudinal muscle (LM) layer in mediating communication between the CM lamellae were studied by simultaneously recording with three surface electrodes, using different types of muscle strip preparations. When the ICC-bSM network was intact, slow waves were observed to be entrained both along and across CM lamellae. In contrast, the CM layer devoid of the ICC-bSM network, the myenteric plexus, and the longitudinal muscle (CM preparation) was spontaneously quiescent. Spike-like action potentials, evoked in the CM preparations by Ba2+ (0.5 mM), were entrained within CM lamellae but were not coordinated between the CM lamellae. In the LM-CM preparations, in which the longitudinal muscle and the ICC-AP network were intact, the Ba(2+)-evoked action potentials were again not coordinated across septa but entrained within CM lamellae. In a step preparation, in which the ICC-bSM network was removed from part of the muscle strip, slow waves were observed to be entrained in areas with and without the ICC-bSM network when electrodes were positioned along septa. When electrodes were positioned across CM lamellae, synchronized slow wave activity was observed only in areas with the intact ICC-bSM network and quiescent activity was recorded in areas devoid of the ICC-bSM network. These results demonstrate that CM cells are electrically coupled within a CM lamella, but not between CM lamellae. The submuscular ICC-bSM network, but not longitudinal or circular muscle cells, nor the ICC-AP, mediates communication between CM lamellae.

Morphologic characterization of polyvinyl sponge (Ivalon) breast prosthesis

BACKGROUND

Although almost all breast implants are made of silicon, some implants, especially the ones used in early augmentation mammoplasty, were made of other materials, one of which is polyvinyl alcohol (commercially known as the Ivalon sponge). The morphology of this type of breast implant and its associated tissue reactions have not been characterized in detail.

MATERIALS AND METHODS

A pair of polyvinyl breast prostheses implanted 40 years ago in a 66-year-old woman were removed together with their capsules to correct progressive disfiguration. The implants and capsules were radiographed. Sections from these specimens were subjected to routine histologic studies and special stains, including periodic acid-Schiff and Masson's trichrome stains.

RESULTS

The breast implants were composed of crystals with a pathognomonic morphology. By hematoxylin-eosin stain, these crystals were polygonal, colorless, and refractile, but nonbirefringent, and they had a characteristic bubbling internal structure. The crystals displayed a deep-blue color with Masson's trichrome stain and were strongly periodic acid-Schiff-positive, with or without diastase digestion. These crystals appeared isolated or interconnecting and were separated from one another by spaces filled with tissue fluid. The capsules were composed of the same kind of crystals, but they were heavily calcified and associated with dense fibrosis and occasional multinucleated giant cells.

CONCLUSIONS

This case serves to emphasize that breast prostheses made of materials other than silicon may be rarely encountered in the surgical pathology laboratory. Although polyvinyl breast implants were abandoned, injection of polyvinyl into various tissues for therapeutic purposes is sometimes indicated. The morphologic features of polyvinyl as detailed in this study should enable prompt and accurate recognition of this material, whether it is in breast implants or other types of tissue.

Cyclopiazonic acid, inhibiting the endoplasmic reticulum calcium pump, reduces the canine colonic pacemaker frequency

The slow wave frequency of the canine colon has previously been hypothesized to be paced by an intracellular biochemical clock. We investigated the relationship between the endoplasmic reticulum (ER) Ca++ and the periodicity of the biochemical clock. Cyclopiazonic acid, a specific inhibitor of the ER Ca++ pump, dose-dependently decreased the pacemaker frequency. Similarly, chelating cytosolic Ca++ with bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetra-acetic acid (BAPTA) also decreased the pacemaker frequency. These observations suggest that delaying the Ca++ uptake into the ER decreases the pacemaker frequency. The pacemaker frequency was similarly decreased by neomycin [inhibiting inositol 1,4,5-triphosphate (IP3) synthesis] and by caffeine at concentrations higher than 5 mM (inhibiting the IP3-sensitive Ca++ channels in the ER membrane). Hence the IP3-sensitive Ca++ stores are involved in the biochemical clock. Ryanodine (up to 60 microM) did not affect the pacemaker frequency, which indicates that a ryanodine-sensitive store, if it exists, is not coupled to the biochemical clock. Electron microscopy showed that the smooth ER forms an extensive network of subsurface cisternae that is closely associated with large areas of the cytoplasmic face of the plasma membrane. These structures were the most extensive in interstitial cells of Cajal, slightly less in branching smooth muscle cells and far less in circular muscle cells. In summary, on the basis of these electrophysiological and morphological observations, we hypothesize that the Ca++ refilling cycle of the IP3-sensitive calcium stores associated with the plasma membrane determines the frequency of the pacemaker activity generated by the submuscular interstitial cells of Cajal-smooth-muscle network of the canine colon.

Shiftwork and heat stress in an intensive care unit

This paper reported the results of investigation on shiftwork and heat stress in an intensive care unit. The aim of this study was to analyse the physiological strain of nurses during the three shifts (Morning, Afternoon, Night) in relation to the specific microclimatic conditions and job activities. 8 professional nurses (6 female and 2 male), aged between 21 and 38 years (mean 29.8 +/- 5.6 years), having from 3 to 18 years service, were monitored throughout a complete working cycle of 4 days. They worked on a three shift system at fast rotation. Their working environment was an independent unit for intensive care and expert surgical treatment which was entirely air conditioned. The observation indexes included: twenty-five blood parameters, ten urine parameters, net cardiac cost and relation cardiac cost, etc. The results of the investigation have not evidenced serious alterations of the psycho-physical conditions of the nurses, but do pointed out some problems pertaining both to the environmental and physiological conditions.

Occupancy of anion binding exosite 2 on thrombin determines Ca2+ dependence of protein C activation

Thrombomodulin (TM) binds thrombin to form a complex that activates the plasma anticoagulant zymogen protein C. TM is an integral membrane glycoprotein that contains a chondroitin sulfate moiety. Interaction with thrombin involves both the protein component of TM, specifically the growth factor-like repeats 4-6 (TM 4-6), and chondroitin sulfate. Removal of chondroitin sulfate decreases the affinity for thrombin approximately 10-fold and shifts the Ca2+ dependence of protein C activation from simple saturation at > or = 500 microM Ca2+ to a distinct optimum at approximately 100 microM Ca2+. Thrombin possesses two regions of high positive charge, anion binding exosites 1 and 2. Anion binding exosite 1 interacts with the growth factor region of TM while exosite 2 is involved in binding prothrombin activation fragment 2 or heparin. We demonstrate that recombinant TM, truncated at the membrane-spanning domain, or TM 4-6 can bind thrombin when fragment 2 is present either covalently attached (meizothrombin des-fragment 1) or in reversible association. With meizothrombin des-fragment 1, the Ca2+ dependence of protein C activation is independent of the presence of the chondroitin sulfate on TM. At 0.27 mM Ca2+, TM containing chondroitin sulfate binds thrombin (Kd(app) = 0.3 nM) approximately 45 times tighter than meizothrombin des-fragment 1 (Kd(app) = 14 nM). However, the chondroitin-free form binds thrombin (Kd(app) = 2.4 nM) only approximately 4 times tighter than meizothrombin des-fragment 1 (Kd(app) = 9.4 nM). These studies suggest that occupancy of anion binding exosite 2 by either chondroitin sulfate or fragment 2 alters thrombin conformation resulting in the altered Ca2+ dependence of protein C activation.

Selective lesioning of interstitial cells of Cajal by methylene blue and light leads to loss of slow waves

Incubation with 50 microM methylene blue (MB) and subsequent intense illumination resulted in abolition of the slow-wave activity in the submuscular interstitial cells of Cajal-circular muscle (ICC-CM) preparations of canine colon. This was often accompanied by a decrease in resting membrane potential. Repolarization of cells back to -70 mV did not restore the slow-wave activity, indicating that MB plus light directly interrupted the generation mechanism of slow waves. After MB incubation, a 2-min illumination consistently changed the mitochondrial conformation in ICCs from very condensed to orthodox, without inducing any obvious changes in smooth muscle cells. After 4- to 10-min illumination, ICCs became progressively more damaged with swollen and ruptured mitochondria, loss of cytoplasmic contrast and detail, loss of caveolae, and rupture of the plasma membrane. No damage was seen in smooth muscle cells or nerves. Gap junctional ultrastructure was preserved. Intense illumination without preincubation with MB left the slow waves and the ultrastructure of ICC-CM preparations unaffected. In CM preparations, without the submuscular ICC-smooth-muscle network, MB plus light induced no changes in electrical activity. We conclude that the correlation between selective damage to the submuscular ICCs (relative to smooth muscle) and selective loss of the slow-wave activity (relative to other electrical activity of the CM) strongly indicates that the ICCs play an essential role in the generation of slow waves.

Canine colonic circular muscle generates action potentials without the pacemaker component

Two dominant types of action potentials in canine colon are slow wave type action potentials (slow waves) and spike-like action potentials (SLAPs). The slow waves, originating at the submuscular surface where a network of interstitial cells of Cajal (ICCs) is found, possess a pacemaker component. Activation of the pacemaker component is insensitive to voltage changes and L-type calcium channel blockers, and is postulated to involve a metabolic clock sensitive to cyclic AMP. SLAPs are more prominent in the longitudinal muscle. To understand the contribution circular muscle cells make to the generation of these action potentials, a circular muscle preparation (devoid of the submuscular ICC-smooth muscle network, longitudinal muscle, and myenteric plexus) was developed. Circular muscle preparations were spontaneously quiescent, with a resting membrane potential of -62.9 +/- 0.6 mV. Ba2+ (0.5 mM) depolarized the cells to -51.8 +/- 0.6 mV and induced electrical oscillations with a frequency, duration, amplitude, and rate of rise equal to 6.6 +/- 0.4 cpm, 2.2 +/- 0.2 s, 19.4 +/- 0.9 mV, and 21.8 +/- 1.7 mV/s, respectively. In most cases, Ba(2+)-induced oscillations were preceded by a prepotential of 4.4 +/- 0.3 mV, with a rate of rise of 1.1 +/- 0.1 mV/s. Ba(2+)-induced oscillations were abolished by 1 microM D600 as well as by repolarization of 6-12 mV. Addition of 0.1 microM Bay K8644 in the presence of Ba2+ further depolarized circular muscle cells to -42.4 +/- 0.8 mV and increased the oscillation frequency to 16.8 +/- 1.8 cpm. The electrical oscillations induced in circular muscle preparations by Ba2+ and Bay K8644 were similar to the SLAPs exhibited by the isolated longitudinal muscle layer, indicating that generation of SLAPs is an intrinsic property of smooth muscle cells. Forskolin (1 microM), previously shown to dramatically decrease the frequency but not the amplitude of slow waves in preparations including the submuscular ICC network, decreased the amplitude of the Ba(2+)-induced oscillations in circular muscle preparations without changing the frequency. These results provide strong evidence for the hypothesis that the submuscular ICC-smooth muscle network is essential for the initiation of the pacemaker component of the colonic slow waves. The mechanism for regulating the frequency of slow waves is different from that responsible for the Ba(2+)-induced oscillations in circular muscle preparations. Circular muscle cells are shown to be excitable and capable of generating oscillatory activity dominated by L-type calcium channel activity, which is regulated by K+ conductance.

Electrical coupling of circular muscle to longitudinal muscle and interstitial cells of Cajal in canine colon

1. Electrical communication between circular muscle, longitudinal muscle and interstitial cells of Cajal (ICC) was investigated; the hypothesis was tested that the resting membrane potential (RMP) gradient in the circular muscle of canine colon is caused by electrical coupling to neighbouring cells. 2. Isolated longitudinal muscle exhibited spike-like action potentials at a RMP of -45 mV with a frequency and amplitude of 20 cycles/min and 12 mV, respectively. 3. The circular muscle (CM), devoid of longitudinal muscle, myenteric plexus and submuscular ICC-smooth-muscle network, was electrically quiescent at a uniform RMP of -62 mV across the entire circular muscle layer. 4. Preparations consisting of only the submuscular ICC network and a few adjacent layers of circular muscle cells exhibited slow wave-type action potentials at a RMP of about -80 mV. 5. In ICC-CM preparations, consisting of the submuscular ICC network and circular muscle, a RMP gradient of 10 mV was observed near the submucosal border, whereas the RMP was constant at -62 mV in the myenteric half of the circular muscle. 6. In full thickness (FT) preparations, a RMP gradient of 23 mV was observed. The RMP decreased gradually from -71 mV at the submucosal border to -48 mV at the myenteric border of the circular muscle. 7. Coupling of longitudinal muscle to circular muscle caused circular muscle cells at the myenteric surface to depolarize by 14 mV and longitudinal muscle cells to hyperpolarize by 3 mV. 8. In the ICC-CM preparations, the slow wave amplitudes did not decay exponentially away from the ICC network indicating that slow waves propagated actively into the circular muscle; in the FT preparations there was an apparent exponential decay but this was due to the RMP gradient. 9. Spike-like action potentials (SLAPs) superimposed on the plateau phase of slow waves did not decay exponentially away from the myenteric border suggesting that SLAPs were generated within the circular muscle layer. 10. In summary, circular muscle cells possess a uniform intrinsic RMP of -62 mV. The RMP gradient in situ is caused by electrical coupling of circular muscle cells to longitudinal muscle cells and the submuscular network of ICC. In situ, slow wave-type action potentials propagate actively into the circular muscle layer, and, dependent on the level of excitation, circular muscle cells actively generate spikes.

Selective accumulation of methylene blue by interstitial cells of Cajal in canine colon

The network of interstitial cells of Cajal (ICC) at the submucosal surface of the canine colon was selectively stained by incubation with 15-50 microM methylene blue for 30-45 min. The network was composed of regularly scattered ICC cell bodies interconnected by long processes. Circular muscle cells were unstained. Staining of neurons was limited to one or two axons within bundles. The ICC network had a thickness of a single cell, since no overlapping of ICC cell bodies was observed. The ICC network connected the circular muscle cells at the submucosal surface across the septa which circumferentially divided the circular muscle into lamellae. Methylene blue at 50 microM slightly decreased the resting membrane potential and increased the duration of slow waves, leading to an increase in the force of phasic contractions, with no significant influence on other slow-wave parameters. Methylene blue produced neither electrophysiological nor mechanical effects on circular muscle preparations from which the submuscular ICC network was removed, indicating that the excitatory effects of methylene blue on the full-thickness circular muscle layer were mediated by ICC. In summary, the three-dimensional aspects of the submuscular ICC network can be visualized after selective staining by methylene blue. This staining does not affect physiological characteristics of smooth muscle cells.

Intercellular communication in smooth muscle

The functioning of a group of cells as a tissue depends on intercellular communication; an example is the spread of action potentials through intestinal tissue resulting in synchronized contraction. Recent evidence for cell heterogeneity within smooth muscle tissues has renewed research into cell coupling. Electrical coupling is essential for propagation of action potentials in gastrointestinal smooth muscle. Metabolic coupling may be involved in generation of pacemaker activity. This review deals with the role of cell coupling in tissue function and some of the issues discussed are the relationship between electrical synchronization and gap junctions, metabolic coupling, and the role of interstitial cells of Cajal in coupling.

The fifth and sixth growth factor-like domains of thrombomodulin bind to the anion-binding exosite of thrombin and alter its specificity

The domain of thrombomodulin that binds to the anion-binding exosite of thrombin was identified by comparing the binding of fragments of thrombomodulin to thrombin with that of Hirugen, a 12-residue peptide of hirudin that is known to bind to the anion-binding exosite of thrombin. Three soluble fragments of thrombomodulin, containing (i) the six repeated growth factor-like domains of thrombomodulin (GF1-6), (ii) one-half of the second through the sixth growth factor-like repeats (GF2.5-6), or (iii) the fifth and sixth such domains (GF5-6), were examined. Hirugen was a competitive inhibitor for either GF1-6 or GF2.5-6 stimulation of thrombin activation of protein C. GF5-6, which binds to thrombin without altering its ability to activate protein C, competed with fluorescein-labeled Hirugen for binding to thrombin. Therefore, all three thrombomodulin fragments, each of which lacked the chondroitin sulfate moiety, competed with Hirugen for binding to thrombin. To determine whether GF5-6 and Hirugen were binding to overlapping sites on thrombin or were interfering allosterically with each other's binding to thrombin, the effects of each thrombomodulin fragment and of Hirugen on the active site conformation of thrombin were compared using two different approaches: fluorescence-detected changes in the structure of the active site and the hydrolysis of chromogenic substrates. The GF5-6 and Hirugen peptides affected these measures of active site conformation very similarly, and hence GF5-6 and Hirugen contact residues on the surface of thrombin that allosterically alter the active site structure to a similar extent. Full-length thrombomodulin and GF1-6 alter the active site structure to comparable extents, but the amidolytic activity of thrombin complexed to thrombomodulin or GF1-6 differs significantly from that of thrombin complexed to GF5-6 or Hirugen. Taken together, these results indicate that the GF5-6 domain of thrombomodulin binds to the anion-binding exosite of thrombin. Furthermore, the binding of GF5-6 to the anion-binding exosite alters thrombin specificity, as evidenced by GF5-6-dependent changes in both the kcat and Km of synthetic substrate hydrolysis by thrombin. The contact sites on thrombin for the GF4 domain and the chondroitin sulfate moiety of thrombomodulin are still unknown.

Excitability of canine colon circular muscle disconnected from the network of interstitial cells of Cajal

The 6 cpm omnipresent slow waves recorded in the circular muscle (CM) layer of canine colon are generated at the submucosal surface of the CM layer. After removal of the submucosal network of interstitial cells of Cajal (ICC), 66% of the CM preparations (25 of 38) were quiescent in Krebs solution. In the presence of carbachol, seven of nine of these spontaneously quiescent CM preparations demonstrated slow wave-like activity with mean frequency, duration and amplitude of 5.9 +/- 0.4 cpm, 2.8 +/- 0.5 s, and 0.8 +/- 0.2 mV, respectively. Similar slow wave-like activities were induced by TEA (seven out of eight quiescent CM preparations) with frequency, duration and amplitude of 6.1 +/- 0.2 cpm, 2.7 +/- 0.5 s, and 1.0 +/- 0.2 mV, respectively, and by BaCl2 (eight of eight quiescent CM preparations) with frequency, duration, and amplitude of 6.3 +/- 0.3 cpm, 1.8 +/- 0.2 s, and 0.5 +/- 0.1 mV, respectively. All the induced activities were abolished in the presence of 1 microM D600. CM preparations with the submucosal ICC network intact (ICC-CM) showed slow wave activity in Krebs solution at a frequency of 6.2 +/- 0.2 cpm, a duration of 3.6 +/- 0.2 s, and an amplitude of 1.0 +/- 0.1 mV (n = 22). When ICC-CM preparations were stimulated by BaCl2, carbachol, or TEA, the slow wave frequency did not change significantly, but the duration increased as well as the amplitude. In the presence of D600, the upstroke of slow waves remained and the frequency was not affected.(ABSTRACT TRUNCATED AT 250 WORDS)

Proteolytic formation of either of the two prothrombin activation intermediates results in formation of a hirugen-binding site

Hirugen, a synthetic dodecapeptide corresponding to the carboxyl-terminal amino acids 53-64 of hirudin, binds within a deep groove in thrombin that contains a cationic region referred to as the anion-binding exosite. This region is important in many of the binary interactions of thrombin with macromolecular substrates and cofactors. Fluorescein-labeled hirugen was used to probe which steps in the prothrombin activation process generate this anion-binding exosite. Two activation cleavage sites exist in bovine prothrombin. Cleavage at Arg274-Thr275 releases the activation fragments to generate the thrombin precursor, prethrombin 2. Cleavage of prothrombin within a disulfide loop at Arg323-Ile324 leads to formation of meizothrombin with no loss of peptide material but with formation of amidolytic activity. Cleavage of the same bond in prethrombin 2 generates thrombin. Hirugen, labeled at the amino terminus with fluorescein isothiocyanate, does not bind to prothrombin but does bind to thrombin (Kd = 9.6 +/- 1.2 x 10(-8) M), prethrombin 2 (Kd = 1.3 +/- 0.1 x 10(-7) M), thrombin-fragment-2 complex (Kd = 1.1 +/- 0.2 x 10(-6) M), and meizothrombin (Kd = 1.6 +/- 0.5 x 10(-8) M). Prothrombin fragment-2 and hirugen both bind independently to thrombin. A ternary complex can form with hirugen and fragment-2 and either thrombin or prethrombin 2, suggesting that fragment-2 and hirugen bind to discrete sites. Hirugen also alters the active site conformation of thrombin as detected by modulation of synthetic substrate hydrolytic activity. These studies suggest that conformational changes, rather than alleviating steric hindrance, are responsible for the formation of the hirugen-binding site during prothrombin activation. Furthermore, this conformational change can be effected by the cleavage of either of the two bonds required for activation of prothrombin.

The region of the thrombin receptor resembling hirudin binds to thrombin and alters enzyme specificity

A thrombin receptor has recently been cloned and the sequence deduced. The sequence reveals a thrombin cleavage site that accounts for receptor activation. The receptor also has an acidic region with some similarities to the carboxyl-terminal region of the leech thrombin inhibitor, hirudin. Synthetic peptides corresponding to the receptor cleavage site (residues 38-45), the hirudin-like domain (residues 52-69), and the covalently associated domains (residues 38-64) were evaluated for their ability to bind to thrombin. Peptides 38-45 and 38-64 were competitive inhibitors of thrombin's chromogenic substrate activity (Ki = 0.96 mM and 0.6 microM, respectively. Residues 52-69 altered the chromogenic substrate specificity, resulting in accelerated cleavage of some substrates and inhibited cleavage of others. The same peptide binds to thrombin and alters the fluorescence emission intensity of 5-dimethylaminonaphthalene-1-sulfonyl (dansyl)-thrombin in which the dansyl is attached directly to the active site serine (Kd = 32 +/- 7 microM). Residues 52-69 displace the carboxyl-terminal peptide of hirudin, indicating that they share a common binding site in the anion exosite of thrombin. These data suggest that the thrombin receptor has high affinity for thrombin due to the presence of the hirudin-like domain and that this domain alters the specificity of thrombin. This change in specificity may account for the ability of the receptor to serve as an excellent thrombin substrate despite the presence of an Asp residue in the P3 site, which is normally inhibitory to thrombin activity.